In 1848, a candidate for Mayor of Chicago, James Hutchinson Woodworth, labelled himself an Independent Democrat to distance himself from what was at the time a corrupt and disorganized Chicago Democratic party organization; he preferred being described as an Independent Democrat rather than as a Whig as that party was itself experiencing a transition. He won election in his first campaign by an overwhelming majority and then was re-elected for a second term. However his Mayoral political success sealed his departure from any further association with the then Illinois Democratic party. When the Whigs in Illinois became the new Republican party, and he was able to confirm that his Abolitionist ideals would be recognized, he registered as a member of the GOP. He subsequently was elected to the United States House of Representatives from Illinois as a member of the GOP. Woodworth served one term in Congress, and return to a banking career in Chicago that spanned the Civil War era and the Reconstruction.

Andrew Jackson Hamilton, in western Texas, was an Independent Democratic member of the United States House of Representatives, but did not run for re-election in 1860.

In the 2006 primary, Joseph Lieberman of Connecticut, a Democratic incumbent U.S. Senator, lost the Democratic nomination for that office to entrepreneur Ned Lamont by a 52% to 48% margin. Lieberman created a new party called the Connecticut for Lieberman Party, obtained its nomination for the seat on the basis of signed petitions, and ran in the general election in November as its candidate—one of five on the ballot in that race. He won with 49.7% of the votes cast for the office.[4] He had stated while campaigning that if elected he would to meet in caucus with the Democrats in the 110th United States Congress, and within the week following the election, he stated[5] that he was "an Independent Democrat, capital I, capital D," and that he had specified as much to the secretary of the Senate. Throughout that Congress, he continued in that caucus (and it remained the majority caucus, with 51 or 50 members, complemented by the 49 or 48 Republicans caucusing together). As of December 2009[update], during the 111th Congress, Lieberman is annotated as "ID-CT" on the U.S. Senate's "contact information" web-page for him,[6] and with "Independent" in the "Party" column (for both the 110th and 111th Congresses) on Congress's "Biographical Directory of the U. S. Congress"[7] page for him.